Targeted memory reactivation during sleep with closed-loop auditory stimuli: Comparing the effects of slow oscillatory up-phase and down-phase cueing on sleep-dependent declarative memory consolidation

In the last decade, an increasing number of studies have demonstrated that using a relatively new technique called ‘targeted memory reactivation’ can modulate and enhance memory consolidation during sleep. This technique is performed by matching specific externally applied sensory stimuli (e.g., sound cues) with target information (e.g., associated word pairs) during wakefulness and then presenting the learned cues during subsequent non-REM sleep. The present study combines this technique with an auditory closed-loop stimulation (ACLS) algorithm, which detects slow oscillations (SOs) and triggers the presentation of the auditory cues precisely during a specific phase of a SO once the EEG signal passes a certain amplitude threshold. SOs are high-amplitude, lowfrequency undulating EEG signals, which represent the hallmark oscillations during slowwave sleep (SWS). Following the widely accepted assumption that SOs play a central role in the consolidation of memory by driving memory reactivation processes during SWS, the present study aimed to identify the optimal time window for the presentation of auditory cues within a single SO during SWS in order to optimize targeted memory reactivation and thus overnight consolidation. The main focus of the study lay thereby on the comparison of the differential benefits on declarative memory retention during two stimulation conditions: SO up-phase and down-phase. For this purpose, auditory stimuli were presented to subjects during non-REM sleep, timed to set in with SO negative peaks during down-phase stimulation conditions, and with SO positive peaks during up-phase stimulation conditions. As SO up states are assumed to represent a state of increased neuronal firing, the hypothesis of this study proposes that auditory cueing in-phase with online detected SO up states leads to better declarative memory consolidation than cueing during SO down states. During the evening of each experimental condition, subjects performed on a paired-associate learning task (PAL task), during which they were presented with each word pair on a screen while the first syllable of the first word was played simultaneously over in-ear headphones. They were first tasked to learn to match syllables with corresponding word pairs and then to recall a word pair when presented with the matching syllable only. Following this learning session of declarative memory contents after reaching a criterion of 60% correctly recalled word pairs, memory performance was tested once immediately and once during a delayed recall session the next morning. The syllables used in the task where of 600-ms length each and were later presented as cues during post-learning nonREM sleep. Contrary to expectations, analyses of behavioral results during up-phase conditions showed no significant declarative memory benefit compared to down-phase conditions. Also, no significant cueing effect could be observed during both conditions. Analyses of subjects’ averaged auditory evoked potential signals showed the typical immediate evoked potential responses for up-phase and down-phase stimulations, indicating correctly performed auditory cueing during both experimental conditions. Additionally, subjects performed on additional cognitive tests and psychometric assessment tasks, the results of which showed no significant differences for both conditions. The hypothesis of the present study, stating that up-phases represent a superior time window for auditory stimulations compared to down-phases of SOs, was not validated. However, the study facilitated new insights into the relatively new field of closed-loop targeted memory reactivation for potential memory enhancement. As was demonstrated in previous research, targeted memory reactivation combined with precise closed-loop auditory stimulation seems not only to represent a non-invasive and effective method to enhance memory consolidation during sleep, but also to hold various potential benefits, particularly in regard to clinical applications in the field of psychotherapy and neurological disorders. As a result, the present study has undeniably demonstrated that further research is still necessary and might benefit from the present study’s findings as many questions remain unanswered, particularly in regard to specific cueing conditions, underlying neural mechanisms, long-term effects, limitations, and potential side effects of the cued memory reactivation technique

Quantitative and functional analysis of the B cell compartment in patients with multiple myeloma

Einleitung: Sekundäre Immundefekte (SID) aufgrund von malignen Erkrankungen und ihrer Therapie erhöhen die Infektanfälligkeit. Beim Multiplem Myelom (MM) stellen Infekte, neben der Erkrankung selbst, die Haupttodesursache dar. Immer intensivere Therapieverfahren führen zwar zu einer besseren Ansprechrate, erhöhen aber durch kumulative Immunsuppression die Infektanfälligkeit. Dabei hat den stärksten Effekt auf das Immunsystem die autologe hämatopoetische Stammzelltransplantation (auto-HSZT). In der Literatur sind sowohl Einschränkungen der zellulären wie auch humoralen Immunantwort beschrieben. Ziel dieser Arbeit ist es die zugrundeliegenden B-Zell-Defekte bei MM Patienten an verschiedenen Behandlungszeitpunkten phänotypisch und funktional genauer zu charakterisieren. Methoden: In dieser Intention wurde peripheres Blut von neudiagnostizierten MM Patienten (ND) sowie von Patienten die eine auto-HSZT durchliefen (vor und nach HSZT) untersucht. Mittels Durchflusszytometrie wurden die B-Zellen sowie die Verteilung der Subpopulationen ex vivo gemessen. Zusätzlich wurde die B-Zellfunktion auf T-Zell-abhängige und T-Zell-unabhängige Stimulationen überprüft. Dafür wurde anhand durchflusszytometrischer Messungen und B-Zell ELISpots die Proliferation und Differenzierung der B-Zellen analysiert. Ergebnisse: Bei MM Patienten konnte eine Reduktion der B-Zellen und ihrer Subpopulationen festgestellt werden, die sich durch Therapie verschlechterten und nach HSZT am stärksten ausfielen. Funktional fiel bei ND und vor HSZT eine eingeschränkte T-Zell-abhängige B-Zellantwort auf. Nach HSZT lag eine gestörte B-Zellantwort sowohl auf T-Zell-abhängige als auch T-Zell-unabhängige Stimulantien vor. In allen Patientengruppen konnte die T-Zell-abhängige Antwort mittels extrinsischer Stimulantien wiederhergestellt werden. Das quantitative Defizit ex vivo nach HSZT konnte durch die Stimulationen nicht ausgeglichen werden. Nach HSZT wurde ein Zusammenhang festgestellt, zwischen der Anzahl der CD19+ B-Zellen sowie Gedächtnis B-Zellen und der gesamten B-Zellfunktion, den Marginalzonen-ähnlichen B-Zellen und der T-Zell-unabhängigen sowie zwischen CD4+ T-Zellen und der T-Zell-abhängige B-Zellfunktion in vitro. Schlussfolgerung: Therapie-naive, wie auch therapierte MM Patienten wiesen eine eingeschränkte B-Zell-Immunität auf, die nach HSZT am stärksten ausgeprägt war. Dominiert haben dabei quantitative Defizite, die insbesondere nach HSZT zu einer eingeschränkten B-Zellfunktion geführt haben. Die Wiederherstellung der Funktion durch T-Zell abhängige Stimulantien und die Korrelation mit CD4+ T-Zellen sprechen für extrinsische Ursachen der B-Zelldefekte. Zudem weisen Korrelationen nach auto-HSZT der CD19+, CD4+, Gedächtnis B-Zellen und Marginalzonen-ähnlichen B-Zellen mit der B-Zellfunktion darauf hin, dass diese in prospektiven Studien als potentielle Biomarker für sekundäre Immundefekte und somit eine mögliche Immunglobulintherapie nach auto-HSZT untersucht werden sollten.Secondary immunodeficiency (SID) due to malignancy and cancer treatment increases the susceptibility for infections. In multiple myeloma patients infections are a major cause for morbidity and mortality. More aggressive therapies lead to a better response rate however simultaneously increase immunosuppression, in particular the standard high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (auto-HSCT). Previous studies reported a hampered humoral and cellular immunity. This study delineates in depth the quantitative and functional B cell defects at different treatment time points and investigates underlying extrinsic or intrinsic drivers. Methods: Peripheral blood of newly diagnosed MM patients and patients receiving auto-HSCT (tested before high-dose chemotherapy and in early reconstitution after HSCT) was studied. Absolute numbers and distribution of B cell subsets were analyzed ex vivo using flow cytometry. Additionally B cell function was assessed with T-dependent and T-independent stimulation assays, analyzing proliferation and differentiation of B cells by flow cytometry and numbers of immunoglobulin secreting cells in ELISpots. Results: Untreated and treated patients presented with a diminished frequency of total CD19+ B cells and B cell subpopulations, while the deficiency was worst after HSCT. Furthermore, an altered B cell subset distribution with high plasmablast frequencies due to inflammation was noticed. Functionally, newly diagnosed patients and those before HSCT showed a reduced T-dependent B cell response. Patients after HSCT presented with both a hampered T-dependent and T-independent B cell function. In all groups T-dependent function could be restored with extrinsic stimulation in vitro. However, the quantitative deficit measured ex vivo after HSCT could not be compensated. A correlation was observed between marginal zone like B cells and the T-independent response, CD4+ T-cells and the T-dependent B cell function as well as counts of CD19+ as well as memory B cells and both B cell responses in vitro. Conclusion: Newly diagnosed, as well as treated MM patients were affected by quantitative deficits and functional impairment most aggravated after HSCT. Functional recovery upon T-dependent in vitro stimulation and correlation with CD4+ T-cell numbers suggest extrinsic drivers for the B cell defects. Our data therefore provides a foundation for therapeutic strategies to address B cell immunodeficiency in MM patients. Observed correlations after HSCT of CD4+, CD19+, memory B and marginal zone like B cell numbers with the B cell function suggest that these markers should be tested in prospective studies as potential biomarkers for SID and hence immunoglobulin substitution after auto-HSCT

OPG und RANKL in der Sulkusflüssigkeit und im Speichel bei Patienten mit behandelter chronischer Parodontitis und osseointegrierten Implantaten

Beim physiologischen Knochenstoffwechsel spielt das OPG/RANKL - System eine zentrale Rolle für das Vorliegen von Knochenauf - und abbau. RANKL fördert die Knochenresorption durch Steigerung der Anzahl und Aktivität funktionsfähiger Osteoklasten über Aktivierung seines osteoklastären Rezeptors RANK. Dieser Prozess wird durch seinen löslichen Antagonisten OPG inhibiert. Das Ziel der vorliegenden Studie war der Nachweis von OPG und RANKL in der Sulkusflüssigkeit und im Speichel bei Patienten mit dentalen Implantaten. 8 behandelte GCP Patienten mit Implantaten und 7 parodontal gesunde Probanden ohne Implantate waren an der Studie beteiligt. Neben den klinischen Parametern (ST, BNS, GI, GR) wurden Proben der Sulkusflüssigkeit und des Speichel entnommen. Die Untersuchung auf OPG und RANKL erfolgte mittels der ELISA-Technik. In der Sulkusflüssigkeit bei den GCP Patienten wurde OPG an den Implantaten in 30% (92,05pmol/l+/-131,84pmol/l) und an den Zähnen in 27% (195,65pmol/l+/-284,83pmol/l) der Proben nachgewiesen. In der Kontrollgruppe war OPG in 22% (80,66pmol/l+/-120,33pmol/l) der Proben nachweisbar. RANKL lag bei den GCP Patienten an 23% der Implantate (50,99pmol/l+/-82,55pmol/l) und 28% der Zähne (24,94pmol/l+/-39,18pmol/l) vor. In der Kontrollgruppe konnte RANKL in 8% (2,78+/-3,51pmol/l) der Proben gemessen werden. Im Speichel der GCP Patienten konnte OPG (0,38pmol/l+/-0,41pmol/l) in allen und bei den Kontrollen (0,53pmol/l+/-0,94pmol/l) in 6 von 7 Proben gemessen werden. RANKL (0,141+/-0,096pmol/l) wurde bei den GCP Patienten in 7 von 8 Proben und bei den Kontrollen (0,344+/-0,482pmol/l) in 4 von 7 Proben nachgewiesen. Weder im Speichel noch in der Sulkusflüssigkeit lagen Korrelationen zwischen OPG, RANKL und den klinischen Parametern vor. Abschließend bleibt festzustellen, dass in der Sulkusflüssigkeit in 20-30% der Proben OPG und RANKL nachweisbar war. Die RANKL Konzentration an den Implantaten der GCP Patienten war deutlich erhöht, jedoch statistisch nicht signifikant. In nahezu allen Speichelproben konnte OPG und RANKL in geringen Konzentrationen gemessen werden. Der Nachweis von OPG und RANKL in der Sulkusflüssigkeit und im Speichel ist ein vielversprechendes diagnostisches Nachweisverfahren für den Knochenstoffwechsel an Zähnen und Implantaten. Insbesondere sollte die Rolle des OPG und RANKL- Systems in der Etablierung und Aufrechterhaltung einer Osseointegration von Implantaten und der Entstehung von periimplantären entzündlichen Erkrankungen näher untersucht werden

Effect of ritonavir on the pharmacokinetics of the benzimidazoles albendazole and mebendazole: an interaction study in healthy volunteers

Background: Benzimidazoles are often used concomitantly with protease inhibitors in patients with helminthic disease and HIV infection. Low bioavailability and extensive first-pass metabolism make benzimidazoles prone to pharmacokinetic drug interactions. The aim of the present study was to investigate potential drug interactions between the benzimidazoles albendazole and mebendazole and the potent CYP3A4 inhibitor ritonavir. Methods: Sixteen healthy volunteers were administered a single oral dose of 1,000mg mebendazole or 400mg albendazole (2 × n = 8). AUC, Cmax, and t1/2 of mebendazole, albendazole, and albendazole sulfoxide were studied in absence and after short-term (2 doses) and long-term (8days) treatment with ritonavir 200mg bid. Results: Pharmacokinetic parameters of albendazole and mebendazole were not changed by short-term administration of ritonavir. However, long-term administration of ritonavir resulted in significant changes in albendazole and mebendazole disposition, with a significant decrease in AUC0-24 (27 and 43% of baseline for albendazole and mebendazole, respectively) and Cmax (26 and 41% of baseline, respectively). Conclusion: The AUC0-24 of benzimidazoles decreased after long-term use of ritonavir, while no changes in pharmacokinetic profiles were observed under short-term administration. These findings might help to optimize benzimidazole efficacy when used in combination with protease inhibitor

A new simulation framework for soil-root interaction, evaporation, root growth, and solute transport

We have developed a general model concept and a flexible software framework for the description of plant-scale soil-root interaction processes including the essential fluid mechanical processes in the vadose zone. The model was developed in the framework of non-isothermal, multiphase, multicomponent flow and transport in porous media. The software is an extension of the open-source porous media flow and transport simulator DuMux to embedded mixed-dimensional coupled schemes. Our coupling concept allows us to describe all processes in a strongly coupled form and adapt the complexity of the governing equations in favor of either accuracy or computational efficiency. We have developed the necessary numerical tools to solve the strongly coupled nonlinear partial differential equation systems that arise with a locally mass conservative numerical scheme even in the context of evolving root architectures. We demonstrate the model concept and its features, discussing a virtual hydraulic lift experiment including evaporation, root tracer uptake on a locally refined grid, the simultaneous simulation of root growth and root water uptake, and an irrigation scenario comparing different models for flow in unsaturated soil. We have analyzed the impact of evaporation from soil on the soil water distribution around a single plant’s root system. Moreover, we have shown that locally refined grids around the root system increase computational efficiency while maintaining accuracy. Finally, we demonstrate that the assumptions behind the Richards equation may be violated under certain conditions

A new simulation framework for soil-root interaction, evaporation, root growth, and solute transport

We have developed a general model concept and a flexible software framework for the description of plant-scale soil-root interaction processes including the essential fluid mechanical processes in the vadose zone. The model was developed in the framework of non-isothermal, multiphase, multicomponent flow and transport in porous media. The software is an extension of the open-source porous media flow and transport simulator DuMux to embedded mixed-dimensional coupled schemes. Our coupling concept allows us to describe all processes in a strongly coupled form and adapt the complexity of the governing equations in favor of either accuracy or computational efficiency. We have developed the necessary numerical tools to solve the strongly coupled nonlinear partial differential equation systems that arise with a locally mass conservative numerical scheme even in the context of evolving root architectures. We demonstrate the model concept and its features, discussing a virtual hydraulic lift experiment including evaporation, root tracer uptake on a locally refined grid, the simultaneous simulation of root growth and root water uptake, and an irrigation scenario comparing different models for flow in unsaturated soil. We have analyzed the impact of evaporation from soil on the soil water distribution around a single plant’s root system. Moreover, we have shown that locally refined grids around the root system increase computational efficiency while maintaining accuracy. Finally, we demonstrate that the assumptions behind the Richards equation may be violated under certain conditions

Potenzialfelder einer ländlichen Bioökonomie

POTENZIALFELDER EINER LÄNDLICHEN BIOÖKONOMIE Potenzialfelder einer ländlichen Bioökonomie / Rupp, Johannes (Rights reserved) ( -